If all goes according to plan, Honolulu's main port may soon get a power source as clean as the water sloshing under its docks.

A consortium of partners headed by the Department of Energy's Sandia National Laboratories is looking to integrate a portable hydrogen fuel cell unit into the operations of Younger Brothers Ltd., the primary shipper of goods throughout the Hawaiian Islands. Its architects say the technology demonstration could serve as a model for similar facilities in ports around the nation.

Composed of four 30-kilowatt fuel cells, the unit would be housed within a 20-foot shipping container that could be floated, lifted or rolled around the dock.

Hydrogen as a fuel source produces zero emissions, and its only waste byproduct is clean water. The relatively high cost of securing hydrogen -- usually by stripping it from natural gas -- has made it historically uncompetitive with other energy sources in most situations, however.

But Honolulu's port is particularly positioned to make use of the technology, said Joe Pratt, project manager at Sandia Labs.

"Because of the specific characteristics of this port, the numbers actually do pencil out," he said. "There's a good probability that this project will be cost-effective."

Much of Hawaii's bulk commodities -- including much of its food -- has to be shipped to the islands from elsewhere, he said. A large portion of this cargo is routed through Honolulu's port, meaning many refrigerated containers sit in port for hours on end before being loaded onto barges and redistributed to the other islands.

Currently, those refrigerated units are powered by large diesel generators. And like so many other things in the Aloha State, the imported diesel fuel is significantly more expensive than it would be on the mainland, opening the playing field to other fuel sources.

"We compared the efficiencies of [the port's] diesel engines versus fuel cells, studied the energy efficiencies at various power levels and estimated the savings and reductions in emissions that would be realized if they were to convert to a fuel cell-powered operation," Pratt said. Because hydrogen fuel cells operate more efficiently at less-than-maximum power, their advantage relative to diesel generators rises, he said.

Hydrogen looks to expand its niche
Hawaii has, in fact, been something of a hotbed for test projects in green energy design. Volcanic in origin, geothermal energy supplies 20 percent of the Hawaii Big Island's energy needs. State regulations and a favorable market have driven the expansion of solar and wind power, and biomass gas is even harvested from landfills in some areas.

Hydrogen, on the other hand, has typically been more of a "niche" energy source, requiring its proponents to seek out just the right vector of cost and convenience to put it to work.

As the technology improves, however, applications for hydrogen as a fuel are expanding.

"The fuel-cell industry has largely moved beyond one-off demonstration projects towards pre-commercialization and even commercialization in certain markets," said Bud DeFlaviis, director of government affairs at the Fuel Cell & Hydrogen Energy Association.

Cost-effective applications for fuel cells have been identified for material handling equipment, as well as primary and backup power for data centers and telecommunication systems, he said.

The Honolulu prototype has likewise been developed with an eye to more extensive proliferation. After the fuel-cell unit is deployed in 2015, the team behind it -- which includes the Department of Transportation's Maritime Administration, the Hawaii Natural Energy Institute and the prototype developer, Hydrogenics Corp. -- will study its performance, in terms of both physical performance and cost-effectiveness. Based on their findings, they hope to design a commercial-ready product that could be purchased and deployed by ports around the country.